Modern aviation relies heavily on pressure measurement devices such as Pitot probes, Pitot static probes, and static ports to determine important flight characteristics such as the altitude, airspeed, and vertical speed of an aircraft. In order for a pressure measurement device to operate correctly, an ambient opening on the pressure measurement device must be kept clear, as must be an internal airway within the pressure measurement device. This can often be difficult given objects which are regularly encountered by pressure measurement systems during operation, such as mud, condensation, debris from bird and insect strikes, volcanic ash, and dust.
Blockage of pressure measurement devices may also result from human error, such as when a pressure measurement device is subjected to paints, or lubricants when maintenance personnel forget to place protective caps over the ambient opening of the pressure measurement device when the device is not in use. Moreover, maintenance personnel may forget to remove such a protective cap before the pressure measurement device is pressed into service.
Regardless of how an obstruction is introduced to a pressure measurement device, once present the obstruction can lead to the failure of the pressure measurement device. Presently, pressure measurement devices are checked visually by pilots and maintenance staff during down time and as part of a preflight checklist. Such visual checks may catch obstructions at or near the ambient opening, but may also miss obstructions found inside a pressure measurement device where an inspector's vision may be obscured.